/lib/pods/SDL/Cookbook/PDL.pod
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1 2=pod 3 4=head1 NAME 5 6SDL::CookBook::PDL -- CookBook for SDL + PDL 7 8PDL provides great number crunching capabilities to Perl and SDL provides game-developer quality real-time bitmapping and sound. You can use PDL and SDL ''together'' to create real-time, responsive animations and simulations. In this section we will go through the pleasures and pitfalls of working with both powerhouse libraries. 9 10 11=head2 CATEGORY 12 13Cookbook 14 15=head1 Creating a SDL Surface piddle 16 17PDL's core type is a piddle. Once a piddle is provided to PDL it can go do a numerous amounts of things. Please see the example in 'examples/cookbook/pdl.pl' that came with this module. 18 19=head2 Creating a simple piddle 20 21First lets get the right modules. 22 23 use PDL; 24 use SDL::Rect; 25 use SDL::Video; 26 use SDL::Surface; 27 use SDL::PixelFormat; 28 29Suppose you want a surface of size (200,400) and 32 bit (RGBA). 30 31 my ( $bytes_per_pixel, $width, $height ) = ( 4, 200, 400 ); 32 33Define the $width, $height and $bytes_per_pixel. Your $bytes_per_pixel is the number of bits (in this case 32) divided by 8 bits per byte. Therefore for our 32 bpp we have 4 Bpp; 34 35 my $piddle = zeros( byte, $bytes_per_pixel, $width, $height ); 36 37Create a normal $piddle with zeros, byte format and the Bpp x width x height dimensions. 38 39 my $pointer = $piddle->get_dataref(); 40 41Here is where we get the actual data the piddle is pointing to. We will have SDL create a new surface from this function. 42 43 my $surface = SDL::Surface->new_from( $pointer, $width, $height, 32, 44 $width * $bytes_per_pixel ); 45 46Using the same dimensions we create the surface using new_form. The width * Bpp is the scanline (pitch) of the surface in bytes. 47 48 warn "Made surface of $width, $height and ". $surface->format->BytesPerPixel; 49 return ( $piddle, $surface ); 50 51Finally make sure that the surface actually has the correct dimensions we gave. 52 53B<NOTE:> $surface->format->BytesPerPixel must return 1,2,3,4. !! 54 55Now you can blit and use the surface as needed; and do PDL operations as required. 56 57 58=head2 Operating on the Surface safely 59 60To make sure SDL is in sync with the data. You must call SDL::Video::lock B<before> doing PDL operations on the piddle. 61 62 SDL::Video::lock_surface($surface); 63 64 $piddle->mslice( 'X', [ rand(400), rand(400), 1 ], [ rand(200), rand(200), 1 ] ) 65 .= pdl( rand(225), rand(225), rand(255), 255 ); 66 67After that you can unlock the surface to blit. 68 69 SDL::Video::unlock_surface($surface); 70 71=head2 Error due to BPP at blitting 72 73When blitting the new surface check for the return value to see if there has been a problem. 74 75 my $b = SDL::Video::blit_surface( 76 $surface, SDL::Rect->new( 0, 0, $surface->w, $surface->h ), 77 $app, SDL::Rect->new( ( $app->w - $surface->w ) / 2, ( $app->h - $surface->h ) / 2, $app->w, $app->h ) 78 ); 79 80 die "Could not blit: " . SDL::get_error() if ( $b == -1 ); 81 82If the error message is 'Blit combination not supported' that means that the BPP is incorrect or inconsistent with the dimensions. 83After that a simple update_rect will so your new surface on the screen. 84 85=head1 AUTHORS 86 87See L<SDL/AUTHORS>. 88 89 90=cut